A mechanical device provided with a power transmission mechanism for transmitting a rotational torque has a clutch or a transmission in the middle of its power transmission path. Connection or disconnection of power is controlled, or a rotation speed or direction is suitably set on the basis of a characteristic of such a mechanical device.
In the prior art, for example, as discussed in Patent Literature 1, there is known a technology in which a forward/backward switching mechanism is arranged in the middle of a power input shaft (drive side), and a frictional cone clutch is employed as a clutch of the forward/backward switching mechanism.